Water Quality Testing

Monthly Water Quality Report

S.O.C.S. test the water quality at 16 locations in the River Ouse catchment on a monthly basis.

Where we Test

For maps showing where the sample sites are, please use the links below -

Bevern Stream

A - Stoneywish

B - Ditchling STW outflow

C -Stocks Farm, Ditchling

Plumpton Mill Stream

Longford Stream

J - Longford Bridge, Spithurst

Ridgewood Stream

K - Lewes Road, Uckfield

L - A22 By-pass, Uckfield

Cockhaise Brook

M - Keysford Lane, H. Keynes

N - Wildboar Bridge

Upper Ouse

O - Avins Bridge, Ardingly

P- Deans Mill, Lindfield

Collecting water to be tested

The society has been taking samples from the Bevern, Plumpton Mill and Northend streams on a regular basis since May 2001. More recently sites on the Rivers Ouse and Uck along with many other tributaries have been included as well. Since 2005 some of the original sites that demonstrated no significant failure of acceptable water quality have been substituted but data recorded retained.

Samples from Sheffield Mill, some way downstream from the Sloop will also be analysed. All these new sites are on the section of the River Ouse that has now been designated as a salmonid water (EU Freshwater Fisheries Directive).

Robin measuring temperature & dissolved Oxygen

Initial measurements of temperature & dissolved oxygen being taken before the water samples are sent away for full analysis.

The intention is to provide evidence that in some cases the water quality falls short of the standards that are laid down in the EC Freshwater Fish Directive 78/659/EEC, even for cyprinid (coarse) fish. For this purpose it is necessary to collect a minimum of twelve samples and calculate an average. We would, of course, like to see the status of the streams upgraded to salmonid standards, which are more rigorous. The samples also help identify isolated cases of pollution, which are reported to the Environment Agency for immediate investigation.

Sam at work in his lab on a water testing Sunday morning

Full analysis of water samples

Already we can show that in the Bevern stream the water quality deteriorates downstream from Ditchling, which is close to the source. This is due in part to the quantity of treated sewage discharged into the water, which is far too high for the current flow rates, especially during drought conditions in the summer.

Each sample is tested for ammonia (usually from sewage effluent), phosphate (from sewage and to a lesser extent from agricultural fertilisers) and dissolved oxygen concentration. Our tests are carried out “in house” using standard scientific test equipment suitable for measuring concentrations of Ammonia (N), Phosphate (PO4) and dissolved Oxygen O2.The test results are published in our Monthly Water Quality Report as they become available.

In Sepember 2007 we started testing Nitrate levels as well. Nitrates are present in sewage effluents and agricultural fertilisers. Their presence in significant amounts causes eutrophication and there are perceived health hazards from their presence in drinking water. In many areas of the UK high amounts of nitrate in ground water has caused concern and there are now designated Nitrate Vulnerable Zones where use of nitrate fertilisers is restricted. We measure the amount of nitrogen derived from the nitrates in our samples (NO3 as N). The EU Freshwater Fisheries Directive does not set parameters for nitrates, but for nitrites (N02) it gives guide values which are shown in the second table below.

S.O.C.S. designated acceptable limit values

Ammonia	< 0.4 mg/l N
Phosphate	< 4 mg/l PO4
Nitrate	< 5mg/l NO3
Dissolved Oxygen	> 3 mg/l O2

The levels set out in the table on the right are S.O.C.S. designated acceptable limit values. These levels have been arbitrarily chosen to reflect what can reasonably be expected in these waters although they are less stringent than the guide values laid down in the directive. These guide values can be found in the table below.

EU Freshwater Fisheries Directive Guide values

	Salmonid	Cyprinid
Ammonia (as N)	< 0.03 mg/l	< 0.16mg/l
Phosphate	< 0.2 mg/l	< 0.4mg/l
Nitrate	< 0.01 mg/l	< 0.03 mg/l
Dissolved Oxygen	50% saturation > 9mg/l 100% saturation > 7mg/l	50% saturation > 8mg/l 100% saturation > 7 mg/l

The dissolved oxygen in pure chalk spring water can vary from 12 mg/litre at 5 degrees centigrade to 8 mg/litre at 25 degrees. The amount of dissolved oxygen present depends upon the temperature. Organic matter (pollution) can consume some oxygen and the water is then partially saturated. The minimum acceptable concentration is 4 mg/litre. Water with 4 mg/litre at 25 degrees would be 50 %saturated (4/8 x100). The percentage saturation is therefore a measure of pollution. Most samples we test are between 50 to 70 % saturated.

EU Freshwater Fisheries Directive Mandatory values

	Salmonid	Cyprinid
Ammonia (as N)	< 0.78 mg/l	< 0.78mg/l
Dissolved Oxygen	50% saturation > 9mg/l 100% saturation > 6mg/l	50% saturation > 7mg/l 100% saturation > 4mg/l
Phosphate	No mandatory limit	No mandatory limit

The Freshwater Fisheries Directive also lays down mandatory parameters for dissolved oxygen and ammonia. These are shown in the table on the right. Note: There is no mandatory limit laid down for the phosphate or Nitrate levels in lotic waters.